366 REPRODUCTIVE ORGANS OF FILICES, 
provided with a ring are called annulate, while those in which it 
is absent are said to be exannulate. 
The spores, which are all of one kind (isosporous or homo- 
sporous), are usually somewhat angular in form, and have two 
Fie. 805. Fie. 806, 
i (e- 
G 
Fig. 805. Sporangia or capsules of a Fern (Marginaria 
verrucosa). s. Sporangium supported on a stalk, p, 
and surrounded by a ring or annulus, which is a 
continuation of the stalk. One sporangium is repre- 
sented as burst on its side, and the contained spores 
in the act of being scattered.— Fig. 806. Under sur- 
face of the prothallium of a Fern, showing archegonia 
ar, antheridia an, and root hairs k. After Berg and 
Schmidt. 
coats like pollen-cells; and like them, also, the outer coat, 
which has a yellowish or brownish colour, is either smooth or 
furnished with little points, streaks, ridges, or reticulations. 
In germination the inner coat is 
first protruded in the form of an 
elongated tube through an aper- 
ture in the outer coat, which ultim- 
ately bursts, and the tubular pro- 
longation, by cell-division, forms 
a thin flat green parenchymatous 
expansion, called a prothallium 
(fig. 806), from which one or 
more root-hairs are commonly 
produced in its earliest stage (fig. 
806, h). On the under surface 
of this body (fig. 806, ar, an) there 
are soon produced two different 
Fig. 807. Side view of an antheridium structures, called antheridia and 
containing a number of sperm-cells archegonia which represent re- 
or mother-cells, se. sp. Antherozoids , 2 : 
escaping from the antheridium spectively the andrcecium and 
after having burst the sperm-cells. gyncoecium of flowering plants ; 
hence the prothallia are monce- 
cious. The antheridia are cellular bodies (fig. 807) containing 
other minute cells called sperm-cells, se, or mother-cells, in each 
of which is developed a little spiral ciliated filament, sp, termed 
